Decision Support System for Lateral Pipe Rehabilitation: Case Study Analysis

Laterals, connecting between the mainline sewer and individual households, have long been considered as a great source of infiltration and inflow (I/I) to municipal wastewater networks. This paper discusses decision support system focusing on a case study database that provides guidelines for the selection of technically viable and cost-effective lateral rehabilitation methods. The objective of this study was to find (1) how a case study database can be utilized to combine a list of parameters regarding lateral rehabilitation, (2) what is the average cost per linear foot per inch diameter ($/lf-in) for lateral rehabilitation, and (3) what are the most popular rehabilitation methods as well as host pipe materials. In order to accomplish these objectives, a questionnaire-based survey was conducted with municipalities and consulting companies across the USA, Canada, and Europe. Based on the data collected from survey and literature study, a list of 34 lateral rehabilitation case studies was summarized in a project database. The typical range of maximum and minimum values were presented for parameters such as lateral diameter, rehabilitated length, duration, and cost per linear foot per inch diameter ($/lf-in) of rehabilitation. It was computed that the average cost per linear foot-inch diameter for lateral rehabilitation methods using CIPP relining, pipe bursting, and flood grouting was about $20, $12, and $8 respectively. Furthermore, the most popular methods of sewer laterals renewal were CIPP relining and pipe bursting. Finally, it was observed that the most common lateral host pipe material was vitrified clay pipe (VCP).